Include an updated resume with as much relevant information as possible about your career as an artist. Make mention of a formal education in art, specialty courses you've taken and awards you've won, if you have these credentials. This type of information gives more credibility to you and your art. The resume can also include a short bio explaining why you became an artist, what types of art you produce and how you get your inspiration.
Compile a list of the galleries in which you have had your art displayed before and the shows in which you have been involved. Even if these galleries and events have been small, your inclusion in them shows gallery managers you are serious about your art and other art experts have recognized it to some degree.
Write a press release for the gallery to distribute to the media in the event that it chooses to display your art. Any gallery manager will likely appreciate the extra effort you take to put together a release the gallery manager can send out to help publicize your exhibition. At the same time, you're also helping draw people to your exhibit.
Put together a testimonial sheet of comments made by art professionals and customers. Ideally, you will have a number of comments and critiques by recognized art professionals from the community, including gallery owners, an art critic at a local newspaper or other well-known artists.
Print high-quality, color images of a number of your pieces of art. If you want a certain assortment of your art to be displayed in the gallery to which you're applying, display this art prominently.
Assemble the resume, bio, gallery list, testimonial sheet and color images of your portfolio into a folder. In addition to the hard copies, provide a DVD of the content so the gallery manager can review it on the computer and share it with others, if desired. Include your complete contact information in the package and drop the press kit off in person.